[RFC PATCH] mtd: spi-nor: handle signal case as failure

[RFC PATCH] mtd: spi-nor: handle signal case as failure

[Nicholas Mc Guire]

 The problem is that stm32_qspi_wait_cmd() will indicate success in case of
 being interrupted. The if condition is incomplete here as
 wait_for_copletion_interruptible_timeout can return -ERESTARTSYS but this
 is not handled by if(!wait_for_completion_interruptible_timeout()).
 While somewhat unlikely it probably would be hard to figure out what went
 wrong if the signal case does occur.

Fixes: commit 0d43d7ab277a ("mtd: spi-nor: add driver for STM32 quad spi flash controller")
Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
---
Problem found by experimental coccinelle script

Its not clear if its sufficient to simply treat this case as failure or
if it might need some debug output to allow differentiation of signal
and timeout case. 

Patch was compile tested with: stm32_defconfig +CONFIG_MTD=y, CONFIG_MTD_SPI_NOR=y,
CONFIG_SPI_STM32_QUADSPI=m

Patch is against v4.11-rc8 (localversion-next is next-20170503)

 drivers/mtd/spi-nor/stm32-quadspi.c  | 10 ++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/stm32-quadspi.c b/drivers/mtd/spi-nor/stm32-quadspi.c
index 1056e74..27147ad 100644
--- a/drivers/mtd/spi-nor/stm32-quadspi.c
+++ b/drivers/mtd/spi-nor/stm32-quadspi.c
@@ -159,6 +159,7 @@ static int stm32_qspi_wait_cmd(struct stm32_qspi *qspi)
 {
 	u32 cr;
 	int err = 0;
+	long timeout = 0;
 
 	if (readl_relaxed(qspi->io_base + QUADSPI_SR) & SR_TCF)
 		return 0;
@@ -167,8 +168,13 @@ static int stm32_qspi_wait_cmd(struct stm32_qspi *qspi)
 	cr = readl_relaxed(qspi->io_base + QUADSPI_CR);
 	writel_relaxed(cr | CR_TCIE, qspi->io_base + QUADSPI_CR);
 
-	if (!wait_for_completion_interruptible_timeout(&qspi->cmd_completion,
-						       msecs_to_jiffies(1000)))
+	timeout = wait_for_completion_interruptible_timeout(
+				&qspi->cmd_completion, msecs_to_jiffies(1000));
+
+	/* since the calling side only cares about success of failure
+	 * returning -ETIMEDOUT even when interrupted should be ok here
+	 */
+	if (timeout == 0 || timeout == -ERESTARTSYS)
 		err = -ETIMEDOUT;
 
 	writel_relaxed(cr, qspi->io_base + QUADSPI_CR);
-- 
2.1.4

Re: [RFC PATCH] mtd: spi-nor: handle signal case as failure

[Cyrille Pitchen]

Hi all,

Le 03/05/2017 à 11:53, Nicholas Mc Guire a écrit :
>  The problem is that stm32_qspi_wait_cmd() will indicate success in case of
>  being interrupted. The if condition is incomplete here as
>  wait_for_copletion_interruptible_timeout can return -ERESTARTSYS but this
>  is not handled by if(!wait_for_completion_interruptible_timeout()).
>  While somewhat unlikely it probably would be hard to figure out what went
>  wrong if the signal case does occur.
> 
> Fixes: commit 0d43d7ab277a ("mtd: spi-nor: add driver for STM32 quad spi flash controller")
> Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
> ---
> Problem found by experimental coccinelle script
> 
> Its not clear if its sufficient to simply treat this case as failure or
> if it might need some debug output to allow differentiation of signal
> and timeout case. 
> 
> Patch was compile tested with: stm32_defconfig +CONFIG_MTD=y, CONFIG_MTD_SPI_NOR=y,
> CONFIG_SPI_STM32_QUADSPI=m
> 
> Patch is against v4.11-rc8 (localversion-next is next-20170503)
> 
>  drivers/mtd/spi-nor/stm32-quadspi.c  | 10 ++++++++--
>  1 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/stm32-quadspi.c b/drivers/mtd/spi-nor/stm32-quadspi.c
> index 1056e74..27147ad 100644
> --- a/drivers/mtd/spi-nor/stm32-quadspi.c
> +++ b/drivers/mtd/spi-nor/stm32-quadspi.c
> @@ -159,6 +159,7 @@ static int stm32_qspi_wait_cmd(struct stm32_qspi *qspi)
>  {
>  	u32 cr;
>  	int err = 0;
> +	long timeout = 0;
>  
>  	if (readl_relaxed(qspi->io_base + QUADSPI_SR) & SR_TCF)
>  		return 0;
> @@ -167,8 +168,13 @@ static int stm32_qspi_wait_cmd(struct stm32_qspi *qspi)
>  	cr = readl_relaxed(qspi->io_base + QUADSPI_CR);
>  	writel_relaxed(cr | CR_TCIE, qspi->io_base + QUADSPI_CR);
>  
> -	if (!wait_for_completion_interruptible_timeout(&qspi->cmd_completion,
> -						       msecs_to_jiffies(1000)))

Ludovic, can we just use wait_for_completion_timeout() instead?
I think so but you surely know better than me :)
Do you plan to receive signal? maybe to abort the current SPI flash command?

Best regards,

Cyrille

> +	timeout = wait_for_completion_interruptible_timeout(
> +				&qspi->cmd_completion, msecs_to_jiffies(1000));
> +
> +	/* since the calling side only cares about success of failure
> +	 * returning -ETIMEDOUT even when interrupted should be ok here
> +	 */
> +	if (timeout == 0 || timeout == -ERESTARTSYS)
>  		err = -ETIMEDOUT;
>  
>  	writel_relaxed(cr, qspi->io_base + QUADSPI_CR);
> 

Re: [RFC PATCH] mtd: spi-nor: handle signal case as failure

[Ludovic BARRE]

On 05/03/2017 11:23 PM, Cyrille Pitchen wrote:
> Hi all,
>
> Le 03/05/2017 à 11:53, Nicholas Mc Guire a écrit :
>>   The problem is that stm32_qspi_wait_cmd() will indicate success in case of
>>   being interrupted. The if condition is incomplete here as
>>   wait_for_copletion_interruptible_timeout can return -ERESTARTSYS but this
>>   is not handled by if(!wait_for_completion_interruptible_timeout()).
>>   While somewhat unlikely it probably would be hard to figure out what went
>>   wrong if the signal case does occur.
>>
>> Fixes: commit 0d43d7ab277a ("mtd: spi-nor: add driver for STM32 quad spi flash controller")
>> Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
>> ---
>> Problem found by experimental coccinelle script
>>
>> Its not clear if its sufficient to simply treat this case as failure or
>> if it might need some debug output to allow differentiation of signal
>> and timeout case.
>>
>> Patch was compile tested with: stm32_defconfig +CONFIG_MTD=y, CONFIG_MTD_SPI_NOR=y,
>> CONFIG_SPI_STM32_QUADSPI=m
>>
>> Patch is against v4.11-rc8 (localversion-next is next-20170503)
>>
>>   drivers/mtd/spi-nor/stm32-quadspi.c  | 10 ++++++++--
>>   1 files changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mtd/spi-nor/stm32-quadspi.c b/drivers/mtd/spi-nor/stm32-quadspi.c
>> index 1056e74..27147ad 100644
>> --- a/drivers/mtd/spi-nor/stm32-quadspi.c
>> +++ b/drivers/mtd/spi-nor/stm32-quadspi.c
>> @@ -159,6 +159,7 @@ static int stm32_qspi_wait_cmd(struct stm32_qspi *qspi)
>>   {
>>   	u32 cr;
>>   	int err = 0;
>> +	long timeout = 0;
>>   
>>   	if (readl_relaxed(qspi->io_base + QUADSPI_SR) & SR_TCF)
>>   		return 0;
>> @@ -167,8 +168,13 @@ static int stm32_qspi_wait_cmd(struct stm32_qspi *qspi)
>>   	cr = readl_relaxed(qspi->io_base + QUADSPI_CR);
>>   	writel_relaxed(cr | CR_TCIE, qspi->io_base + QUADSPI_CR);
>>   
>> -	if (!wait_for_completion_interruptible_timeout(&qspi->cmd_completion,
>> -						       msecs_to_jiffies(1000)))
> Ludovic, can we just use wait_for_completion_timeout() instead?
exactly, I would use _interruptible extension to allow "user" to
abort a long transfer (without wait the end of command transfert).
But it's not crucial for stm32_qspi, this could be replace by
wait_for_completion_timeout.
sorry to disturb the "mtd pull" :-(

Best regards,
Ludo
> I think so but you surely know better than me :)
> Do you plan to receive signal? maybe to abort the current SPI flash command?
>
> Best regards,
>
> Cyrille
>
>> +	timeout = wait_for_completion_interruptible_timeout(
>> +				&qspi->cmd_completion, msecs_to_jiffies(1000));
>> +
>> +	/* since the calling side only cares about success of failure
>> +	 * returning -ETIMEDOUT even when interrupted should be ok here
>> +	 */
>> +	if (timeout == 0 || timeout == -ERESTARTSYS)
>>   		err = -ETIMEDOUT;
>>   
>>   	writel_relaxed(cr, qspi->io_base + QUADSPI_CR);
>>

Re: [RFC PATCH] mtd: spi-nor: handle signal case as failure

[Nicholas Mc Guire]

On Thu, May 04, 2017 at 09:40:11AM +0200, Ludovic BARRE wrote:
> On 05/03/2017 11:23 PM, Cyrille Pitchen wrote:
> >Hi all,
> >
> >Le 03/05/2017 à 11:53, Nicholas Mc Guire a écrit :
> >>  The problem is that stm32_qspi_wait_cmd() will indicate success in case of
> >>  being interrupted. The if condition is incomplete here as
> >>  wait_for_copletion_interruptible_timeout can return -ERESTARTSYS but this
> >>  is not handled by if(!wait_for_completion_interruptible_timeout()).
> >>  While somewhat unlikely it probably would be hard to figure out what went
> >>  wrong if the signal case does occur.
> >>
> >>Fixes: commit 0d43d7ab277a ("mtd: spi-nor: add driver for STM32 quad spi flash controller")
> >>Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
> >>---
> >>Problem found by experimental coccinelle script
> >>
> >>Its not clear if its sufficient to simply treat this case as failure or
> >>if it might need some debug output to allow differentiation of signal
> >>and timeout case.
> >>
> >>Patch was compile tested with: stm32_defconfig +CONFIG_MTD=y, CONFIG_MTD_SPI_NOR=y,
> >>CONFIG_SPI_STM32_QUADSPI=m
> >>
> >>Patch is against v4.11-rc8 (localversion-next is next-20170503)
> >>
> >>  drivers/mtd/spi-nor/stm32-quadspi.c  | 10 ++++++++--
> >>  1 files changed, 10 insertions(+), 2 deletions(-)
> >>
> >>diff --git a/drivers/mtd/spi-nor/stm32-quadspi.c b/drivers/mtd/spi-nor/stm32-quadspi.c
> >>index 1056e74..27147ad 100644
> >>--- a/drivers/mtd/spi-nor/stm32-quadspi.c
> >>+++ b/drivers/mtd/spi-nor/stm32-quadspi.c
> >>@@ -159,6 +159,7 @@ static int stm32_qspi_wait_cmd(struct stm32_qspi *qspi)
> >>  {
> >>  	u32 cr;
> >>  	int err = 0;
> >>+	long timeout = 0;
> >>  	if (readl_relaxed(qspi->io_base + QUADSPI_SR) & SR_TCF)
> >>  		return 0;
> >>@@ -167,8 +168,13 @@ static int stm32_qspi_wait_cmd(struct stm32_qspi *qspi)
> >>  	cr = readl_relaxed(qspi->io_base + QUADSPI_CR);
> >>  	writel_relaxed(cr | CR_TCIE, qspi->io_base + QUADSPI_CR);
> >>-	if (!wait_for_completion_interruptible_timeout(&qspi->cmd_completion,
> >>-						       msecs_to_jiffies(1000)))
> >Ludovic, can we just use wait_for_completion_timeout() instead?
> exactly, I would use _interruptible extension to allow "user" to
> abort a long transfer (without wait the end of command transfert).
> But it's not crucial for stm32_qspi, this could be replace by
> wait_for_completion_timeout.
> sorry to disturb the "mtd pull" :-(
>
ok - so would you take care of this then - I guess it makes more
sense for the patch to come from someone that understand the context
than from someone that just pinpionted an inconsistency in API use.

thx!
hofrat